1. Field of the Invention
The present invention relates to a printed-circuit board.
2. Description of the Related Art
A structure for dispersing stress generated in a printed-circuit board has been disclosed, for example, in the Japanese Unexamined Patent Publication No. 6-85005. According to this structure, a resin having a coefficient of linear thermal expansion smaller than that of the printed-circuit board is filled in a gap between the printed-circuit board and a semiconductor chip mounted on the board, and expansion and contraction of the printed-circuit board is suppressed in accordance with a difference between a linear thermal expansion of the filled resin and of the printed-circuit board so that a thermal stress generated in the printed-circuit board is dispersed.
There are some problems, however, in the above structure as explained briefly below. That is, according to this structure, an effect of stress dispersion in the printed-circuit board is influenced by a state of the resin filled to the gap and a dispersion of the composition of the filled resin. As a result, cracks occur in a boundary portion between a conductive pattern (e.g., an electrode pattern) and an insulated layer. The above problem will be explained in detail with reference to FIG. 4 below.